FederalTimes explains "the Roth option is expected to primarily benefit military service members and select groups of federal employees, such as judges. Most federal employees are likely to have lower incomes and lower taxes in retirement than they do while working and making contributions, and would not benefit from a Roth investment option."

However, Senior Correspondent Mike Causey explains, the "Roth is attractive to many people, especially younger workers, because it is funded with after-tax money. That means all of the earnings from your investment (remember when that was a possibility?) are yours, tax-free when you start tapping your account."